Workers supplying Jaguar Land Rover's UK production line have been accused of "recklessly" endangering UK growth prospects after voting for a strike that threatens to close key assembly lines within weeks.

The comments were made by the delivery group DHL after its 1,000 employees serving Jaguar's Midlands plants at Castle Bromwich and Solihull voted for a walkout last week as a pay row escalated. They also come as a further 800 DHL workers at Jaguar's Halewood, Merseyside, factory are to vote on industrial action on Monday and despite bosses at the carmaker pleading for management and leaders of the Unite trade union to return to the negotiating table.

In a statement issued on Sunday, DHL said it was "extremely disappointed that Unite has rejected our very generous offer and voted in favour of industrial action", before suggesting that it was now prepared to bypass striking workers.

"Detailed contingency plans are in place to minimise disruption to the customer and we strongly urge the union to reconsider its reckless action and give a clear message to our customer and employees that Unite supports UK growth," the logistics company added.

The confrontational language by DHL contrasts starkly with the more measured tones of other players involved. A Unite spokesman said the dispute was "at the very beginning of the process" and the union hoped to resolve differences through negotiation. Meanwhile, a spokesman for the carmaker, which is not involved in the dispute, said: "Jaguar Land Rover is disappointed that DHL Unite members have voted in favour of industrial action. We encourage a return to the negotiating table to reach a satisfactory outcome for all parties as soon as possible."

DHL staff deliver parts to the carmaker's production lines and often work alongside colleagues on more lucrative Jaguar contracts. They are demanding a pay rise to put them on similar terms and conditions, although management argues that the logistics workers are demanding to be paid more than their Jaguar colleagues.

DHL has offered staff a 4.5% pay increase for 2013, plus a guaranteed 3% for 2014. Unite is asking for 12.8% over two years for employees who sort parts and 20.6% for drivers. About 74% of the Midlands staff voted in favour of taking industrial action.

The popularity of new models has resulted in waiting lists for the Land Rover Evoque, which is manufactured at Halewood, while the first Jaguar F-Type cars emerged from the Castle Bromwich plant in May. In January the company said it would be taking on 800 more people to build new Range Rover models at its factory in Solihull.

The business generates yearly export revenues of about £11bn, with almost 80% of Land Rovers exported to 169 countries and 70% of Jaguars shipped to 63 countries.

The company has more than 16,000 employees, predominantly in Britain, including some 3,500 engineers at two product development centres in Whitley in Coventry, and Gaydon in Warwickshire.